According to the Centers for Disease Control and Prevention (CDC), trauma accounts for 42 million emergency department visits and 2 million hospital admissions across the USA every year. In the USA, trauma accounts for 38.4 deaths per 100,000 of population. Trauma is especially a leading cause of death in the young population, and accounts for 30% of all life years lost in the USA (compared to 16% for cancer, and 12% for heart diseases). Head injury in particular counts for 30% of total trauma cases. Trauma is also the 5th leading cause of death worldwide.
Ultrasound is often the first imaging examination of patients with major trauma. Ultrasound is non-invasive and portable and is available at low cost compared to computed tomography (CT) or magnetic resonance imaging (MRI).
The FAST (Focused Assessment with Sonography in Trauma) protocols were developed to streamline the process of quick examinations of a trauma patient in the emergency room (ER) by relatively untrained users. The aim of the FAST examination is to assess blood accumulation in four areas in the abdomen/chest, where under normal conditions blood would not be present. For instance in the RUQ examination, the user is examined for dark hypoechogenic areas in the Morrison's pouch, the space between the liver and right kidney, where the hypoechogenicity would indicate presence of accumulated blood.
However there is no equivalent FAST examination to quickly detect and monitor intra-cranial blood. This is most likely due to the need to be able to obtain a good scan and interpret intracranial ultrasound images, both of which require considerable skill.
In addition to trauma events, another cause for intracranial bleeding is intracerebral hemorrhagic stroke, which accounts for 10-15% of all strokes and occurs due to rupture of blood vessels in the brain due to hypertension. In patients suspected of having suffered a stroke event it is necessary to quickly assess whether or not there is bleeding, so that proper drugs can be administered in a timely manner. In addition, hemorrhagic transformation is a natural consequence of ischemic stroke. It is exacerbated by the administration of clot-dissolving medicine such as tPA, and the hemorrhagic transformation can have more devastating effects than the original stroke itself.
In most situations involving head trauma or hemorrhagic stroke, it is necessary to monitor the patient over a period of time. For instance in trauma, it is necessary to monitor whether additional bleeding has occurred as evidenced by changes in the size of the blood pool. Some hemorrhages develop inside areas of ischemia (“hemorrhagic transformation”), which needs monitoring over a period of time.
Currently, a device, described in U.S. Pat. No. 8,060,189 to Dor et al. (hereinafter “the '189 patent”), known as Infrascanner that uses near infra-red light is available to detect peripheral blood in the brain (mostly epidural and subdural hematomas), but the device can work only up to a limited depth of 2.5 centimeters.